I’m somewhat sorry to open these questions bellow an article of a particular artist. I see that Bayard Wu has a lot going for him in terms of diligence and talent.

And, of course, Rembrandt and Goya can be said to be predominantly gloomy, too. A comparison with them could help me refine my initial puzzlement. Goya and Rembrandt have apparently much more to say. They show a much wider variety of themes. Perhaps you can help me with your own knowledge and observations.

Subjects in the concept art field are driven by the economics of the industries the artists serve, primarily gaming and film. If you look at the subjects and themes of the most popular video games, you’ll immediately see where the “predominance and persistence of gloomy and disquieting subjects” you have noticed find their origin. In that context, Wu’s subjects are positively buoyant compared to the deliberately gruesome and disturbing subjects of some.